Optimizing the Properties of La0.8Sr0.2CrO3 Thin Films through Post-Annealing for High-Temperature Sensing

La0.8Sr0.2CrO3 (0.2LSCO) thin films were prepared via the RF sputtering method to fabricate thin-film thermocouples (TFTCs), and post-annealing processes were employed to optimize their properties to sense high temperatures. The XRD patterns of the 0.2LSCO thin films showed a pure phase, and their crystallinities increased with the post-annealing temperature from 800 degrees C to 1000 degrees C, while some impurity phases of Cr2O3 and SrCr2O7 were observed above 1000 degrees C. The surface images indicated that the grain size increased first and then decreased, and the maximum size was 0.71 mu m at 1100 degrees C. The cross-sectional images showed that the thickness of the 0.2LSCO thin films decreased significantly above 1000 degrees C, which was mainly due to the evaporation of Sr2+ and Cr3+. At the same time, the maximum conductivity was achieved for the film annealed at 1000 degrees C, which was 6.25 x 10(-2) S/cm. When the thin films post-annealed at different temperatures were coupled with Pt reference electrodes to form TFTCs, the trend of output voltage to first increase and then decrease was observed, and the maximum average Seebeck coefficient of 167.8 mu V/degrees C was obtained for the 0.2LSCO thin film post-annealed at 1100 degrees C. Through post-annealing optimization, the best post-annealing temperature was 1000 degrees C, which made the 0.2LSCO thin film more stable to monitor the temperatures of turbine engines for a long period of time.

Automated summary

La0.8Sr0.2CrO3 (0.2LSCO) thin films were prepared using the RF sputtering method for thin-film thermocouples (TFTCs), with post-annealing processes optimizing properties for high-temperature sensing. XRD patterns showed pure phase with crystallinities increasing up to 1000 degrees C. The 0.2LSCO thin films exhibited improved stability and conductivity when annealed at 1000 degrees C, making them suitable for long-term monitoring of turbine engine temperatures.